K2Mn4O8/Reduced Graphene Oxide Nanocomposites for Excellent Lithium Storage and Adsorption of Lead Ions

Ion diffusion efficiency at the solid-liquid interface is an important factor for energy storage and adsorption from aqueous solution. Although K2Mn4O8 (KMO) exhibits efficient ion diffusion and ion-exchange capacities, due to its high interlayer space of 0.70nm, how to enhance its mass transfer performance is still an issue. Herein, novel layered KMO/reduced graphene oxide (RGO) nanocomposites are fabricated through the anchoring of KMO nanoplates on RGO with a mild solution process. The face-to-face structure facilitates fast transfer of lithium and lead ions; thus leading to excellent lithium storage and lead ion adsorption. The anchoring of KMO on RGO not only increases electrical conductivity of the layered nanocomposites, but also effectively prevents aggregation of KMO nanoplates. The KMO/RGO nanocomposite with an optimal RGO content exhibits a first cycle charge capacity of 739mAhg(-1), which is much higher than that of KMO (326mAhg(-1)). After 100 charge-discharge cycles, it still retains a charge capacity of 664mAhg(-1). For the adsorption of lead ions, the KMO/RGO nanocomposite exhibits a capacity of 341mgg(-1), which is higher than those of KMO (305mgg(-1)) and RGO (63mgg(-1)) alone.